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This Article Full Text Full Text (PDF) All Versions of this Article: 99/5/2369    most recent 00320.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Reynolds, J. S. Articles by Gdowski, G. T. PubMed PubMed Citation Articles by Reynolds, J. S. Articles by Gdowski, G. T.

Head Movements Produced During Whole Body Rotations and Their Sensitivity to Changes in Head Inertia in Squirrel Monkeys

University of Rochester, Departments of Biomedical Engineering and Neurobiology and Anatomy, Rochester, New York

Submitted 21 March 2007; accepted in final form 23 February 2008

The head's inertia produces forces on the neck when the body moves. One collective function of the vestibulocollic and cervicocollic reflexes (VCR and CCR) is thought to be to stabilize the head with respect to the trunk during whole body movements. Little is known as to whether their head-movement kinematics produced by squirrel monkeys during whole body rotations are similar to those of cats and humans. Prior experiments with cats and human subjects have shown that yaw head-movement kinematics are unaffected by changes in the head's inertia when the whole body is rotated. These observations have led to the hypothesis that the combined actions of the VCR and CCR accommodate for changes in the head's inertia. To test this hypothesis in squirrel monkeys, it was imperative to first characterize the behavior of head movements produced during whole body rotation and then investigate their sensitivity to changes in the head's inertia. Our behavioral studies show that squirrel monkeys produce only small head movements with respect to the trunk during whole body rotations over a wide range of stimulus frequencies and velocities (0.5–4.0 Hz; 0–100°/s). Similar head movements were produced when only small additional changes in the head's inertia occurred. Electromyographic recordings from the splenius muscle revealed that an active process was utilized such that increases in muscle activation occurred when the inertia of the head was increased. These results are consistent with prior cat and human studies, suggesting that squirrel monkeys have a similar horizontal VCR and CCR.

This article has been cited by other articles:

				J. S. Reynolds, D. Blum, and G. T. Gdowski Reweighting Sensory Signals to Maintain Head Stability: Adaptive Properties of the Cervicocollic Reflex J Neurophysiol, June 1, 2008; 99(6): 3123 - 3135. [Abstract] [Full Text] [PDF]